|Yokomi, Raymond - Ray|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/2/2007
Publication Date: 7/1/2007
Citation: Mello, A.F., Fletcher, J., Yokomi, R.K. 2007. Spiroplasma citri Infection Affects Yield and Fruit Quality in Commercial Citrus Grove in California. Phytopathology. 97:S74.
Technical Abstract: The chronic effects of stubborn disease, caused by Spiroplasma citri, on citrus include stunting, abnormal fruit shape and reduced yield. However, disease impact have never been quantified in a commercial grove. The objective of this work was to measure the impact of S. citri infection on tree development, yield and fruit quality. Ten infected (both symptomatic and asymptomatic) and 10 healthy navel orange trees, cv. Thompson Improved on Carrizo rootstock were selected in a 20-year old grove in northeastern Kern Co. CA. Measurements included tree height and width, rootstock and scion diameters, yield weight and fruit drop in October, 2006. Thirty fruits per tree were measured, weighed and evaluated for peel color, sunburn, shape and cracks. The juice was extracted and weighed, and total soluble solids and titratable acidity were measured. Fruits from infected trees were lighter, smaller in size, and more likely to be mis-shapen than those from healthy trees, but significant yield reduction occurred only in severely symptomatic trees. All the other variables were statistically indistinguishable between infected and healthy trees. The significant reduction in fruit yield and quality associated with S. citri infection validate the concern among citrus growers in central California that stubborn disease can result in a significant constraint to production.